This invention relates to a chair control mechanism, and more particularly to various features enhancing the operation and flexibility of a chair control mechanism of the mid-pivot type.
Various chair control mechanisms are known, for controlling the position of a chair seat relative to a seat support, such as an upstanding chair support pedestal. Typically, a chair control mechanism provides a seat pivot feature for providing pivoting movement of the seat relative to the seat support, as well as a lockout feature for selectively maintaining the seat in a predetermined angular position relative to the seat support. Some types of chair control mechanisms also provide a back mounting feature for supporting the chair back. Some designs simply support the chair back at a predetermined position relative to the seat, while others provide controlled movement of the back in response to changes in the seat angle, such that the seat and back move in a synchronous fashion upon movement of the seat.
It is an object of the present invention to provide a chair control mechanism which functions to support both the seat and the back of a chair. It is another object of the invention to provide such a chair control mechanism which includes a feature for adjusting the range of pivoting movement of the seat relative to the seat support. Yet another object of the invention is to provide such a chair control mechanism in which the angle of the seat can be selectively fixed in a predetermined position relative to the seat support. A still further object of the invention is to provide such a chair control mechanism which provides independent movement of the chair back relative to the seat. A still further object of the invention is to provide such a chair control mechanism which includes a lockout feature for the chair back, to enable the chair back to be fixed in a predetermined angular position relative to the seat regardless of the position of the seat relative to the seat support.
In accordance with the invention, a chair control mechanism adapted to be positioned between a seat support and a seat, includes a base member secured to the seat support and a seat mounting member pivotably engaged with the base member for movement about a seat pivot axis. The seat is adapted to be mounted to the seat mounting member, and an adjustable spring is interposed between the base member and the seat mounting member for biasing the seat toward a predetermined position relative to the seat support. A variable position seat locking arrangement is interposed between the base member and the seat mounting member for selectively retaining the seat in one of a series of predetermined positions against the force of the spring. The variable position seat locking arrangement may include one or more locking pins interconnected with a manually operated actuator mechanism, and each locking pin is selectively engageable within one of a series of seat locking openings formed in a retainer member associated with the seat mounting member. The manually operable actuator mechanism includes a handle and an actuator member which is operable to selectively move one of the seat locking pins into engagement within one of the seat locking openings.
The seat mounting member includes a back mounting arrangement for pivotably mounting the back to the seat mounting member, for movement about a back pivot axis. The back mounting arrangement includes a back pivot member fixed to the seat mounting member at a location rearwardly of the seat pivot axis. A back mounting bracket is pivotably engaged with the back mounting member, so as to be pivotable relative to the seat mounting member about the back pivot axis which is defined by the back mounting member. With this arrangement, the seat is pivotable about the seat pivot axis relative to the seat support member, and the back is independently pivotable about the back mounting member relative to the seat. A biasing arrangement, such as a torsion spring, is interposed between the seat mounting member and the back mounting bracket for biasing the back forwardly relative to the seat. A variable position back locking arrangement is interposed between the seat mounting member and the back mounting bracket. The variable position back locking arrangement is preferably located forwardly of the back mounting member, and includes one or more back locking pins, each of which is selectively engageable within one of a series of spaced openings associated with the back mounting bracket, for selectively locking the back at a predetermined angle relative to the seat against the force of the spring.
The invention also includes a system for adjusting the range of pivoting movement of the seat relative to the seat support. This aspect of the invention involves the use of a front pivot stop arrangement and a rear pivot stop arrangement, preferably in combination so as to control the range of pivoting movement of the seat relative to the seat support.
The front pivot stop arrangement may be in the form of stop structure associated with either the base or the seat support member of the chair control mechanism, and an engagement member associated with the other of the base member and the seat support member. The stop structure may be in the form of a stop member mounted to the seat support member. The stop member defines an upwardly facing stop surface and one or more slots extending from the stop surface. The engagement member is preferably mounted to the seat support member, and is shiftable between first and second positions. In its first position, the engagement member engages the upwardly facing stop surface of the stop member so as to limit the forward pivoting movement of the seat support member relative to the base member to a first angular position. When shifted to its second position, the engagement member is aligned with one of the slots in the stop member and is receivable within the slot so as to enable the seat mounting member to be pivoted to a second angular position relative to the base section. The engagement member is preferably mounted to a manually operable handle, which can be manipulated by a user to place the engagement member in either its first position or its second position. The stop member and the engagement member are preferably located forwardly of the seat pivot member so as to control the forward pivoting movement of the seat relative to the seat support.
Opposite the stop member and the engagement member, one or more pivot stop members are interposed between the seat support member and the base member for limiting pivoting movement of the seat in the opposite direction of pivoting movement. The one or more pivot stop members are preferably stationarily mounted to the base member rearwardly of the seat pivot member, and each pivot stop member defines a stop surface engageable by the seat support member when the seat support member is pivoted relative to the base member, for limiting pivoting movement of the seat relative to the seat support. In this manner, the height of the stop surface of the pivot stop member determines the angle at which the seat support member engages the stop surface. The pivot stop member is selected from different pivot stop members of varying height, such that the height of the stop surface of the pivot stop member is selected according to the desired pivot angle of the seat support member relative to the base member, to limit the angle of the seat relative to the seat support. In a preferred form, the one or more stop members are selected and placed at the time of manufacture of the chair control mechanism, and are enclosed by the structural components of the chair control mechanism during use. The pivot stop members are preferably employed to limit the range of rearward pivoting movement of the seat support member relative to the base member, and thereby the rearward pivoting angle of the seat relative to the seat support.
The various aspects of the invention can be utilized individually to provide selective enhancements in the features and functioning of a chair control mechanism, or can be used in combination to provide a chair control mechanism with significant enhancements in flexibility in manufacture and operation.